Soften the butter to room temperature while preheating the oven to 350 degrees. Mix the cheese spread into the butter and stir in the mayonnaise. Add garlic powder and stir until all is completely blended - no lumps. Gently stir in crabmeat.
Slice the muffins in half and divide the crab mixture on the 12 halves. Cut each half into quarters and place them on a baking sheet. Bake in the oven until the cheese is bubbly and the edges are brown. Serve at once. The spread can be made in advance and refrigerated for a couple of days. These may also be frozen before cooking for later use. Make the muffins up and cut into quarters.
Freeze them on cookie sheets, and then place them in the freezer in zip-loc bags for storage. They will keep a month or two without losing much flavor.